www/chromium: fix obtaining HOST_NAME_MAX

Using sysconf(3) API lead to accidental introduction of variable length arrays
(VLA) in the port. Additionally gethostname(3) has been passed _SC_HOST_NAME_MAX
incorrectly as the HOST_NAME_MAX length.

Fall back to using _POSIX_HOST_NAME_MAX as the remaining code is not ready for
introducing sysconf(3) as a patch.

Bump PORTREVISION to rebuild with the new patch.

Reviewed by: bapt
Sponsored by: Fudo Security
Differential Revision: https://reviews.freebsd.org/D30062